A research program is proposed to develop and evaluate a thermodilution technique for detecting and quantitating left-to-right and right-to-left cardiovascular shunts in neonates. The mathematical methods for the measurements have been developed and demonstrated at this institution. In the proposed program software for on-line processing will be developed. Accuracy of the method will be determined in newborn lambs and in patients with shunts due to conqenital cardiac defects. After extensive experience has been obtained with the method and safety aspects have been thoroughly evaluated, the thermodilution system will be integrated with CABAS (Computer Automated Blood Gas Monitoring System) and applied in ICU monitoring of neonates.